Reduction of noise generated by aircraft both around and within the aircraft is of increasing importance. Near field noise outside of the aircraft can create pressure fluctuations that can be fatiguing to the structure of the aircraft. This near field noise can also result in interior noise in the fuselage that makes the aircraft less desireable to passengers.
Propeller driven aircraft have near field and interior noise that include frequency content related to operation of the propeller. Various methods are employed to reduce propeller noise, including the use of swept six bladed propellers, active noise control, and tuned mechanical dampers within or on the fuselage. On multi engine aircraft, angular phasing of the propellers has long been used to alter the noise characteristics within the fuselage from the propellers. Often, propellers are placed close to the air inlet for the engine so as to provide boosted inlet pressure and a "supercharging" effect on the engine.
In spite of the various methods used to reduce noise from propeller driven aircraft, there remains a need for further improvement. The present invention does that in a novel and unobvious way.